At the present time there is a growing interest for lithium batteries. The interest is not limited to primary batteries, which so far have been most common on the market, but is increasingly focused also on secondary batteries. Lithium metal is attractive as a battery anode material because of its light weight, high voltage, high electrochemical equivalence, and good conductivity.
However, the use of pure lithium as anode material creates numerous and difficult problems, which are well known in the art. Especially, the difficulty with rechargeability and low melting point should be mentioned. The safety problems with batteries having pure lithium negative electrodes can certainly not be neglected.
For improving the qualities of negative electrodes having lithium as the active material the use of different lithium alloys has been investigated. Especially the use of aluminum as host metal for the highly reactive lithium has been found to provide certain advantages, for example with regard to the absence of dendrite formation and a high melting point. The present invention accordingly relates to a new and improved method for producing a Li(Al) anode for use in a primary or secondary battery.
The production of a Li(Al) powder in the way set forth in the introduction above is known from GB-A-1 484 650, but this powder is then pressed on a current conductive mesh.
In Journal of Electrochemical Society, Volume 124, No 10, 1977, M. L. Rao et al, "Lithium-Aluminium Electrode", p 1490-1492, a method to sinter Li(Al) powder on current conductive grids is disclosed.
In Journal of Electrochemical Society, Volume 131, No 8, 1984, A. S. Baranski et al, "The Cycling Efficiency of Lithium-Aluminium Electrodes in Nonaqueous Media", p 1750-1755, the electrodeposition of lithium on aluminium or nickel wires is disclosed.
By US-A-4 011 372 it is known to east a Li(Al) alloy on a conductive substrate.
Also DE-A-1 049 949 regarding the production of a certain electrode by pressing active lead paste on a lead thread, followed by the step of providing the electrode with a separator should be mentioned as another example of the prior art.
All these publications fail to disclose any totally satisfactory method of practically producing a Li(Al) anode for a lithium battery with the properties and qualities now sought for.